KRT7 and neoplasm: The extrahepatic pancreatobiliary immunohistochemical profile is characterized by expression of a considerable number of markers (Fig 4A and 4C, S2 Fig), including cytokeratins (CK7, CK17, and CK19), mucins (MUC1 and MUC5AC), and tumor-associated epithelial markers (CA19-9, monoclonal CEA, CA125, and maspin).